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System DMA
112
Direct Memory Access (DMA) Support
Prio_0 : Channel priority
-
Prio_0 = 1: The channel has the high-priority level.
Prio_0 = 0: The channel has the low-priority level.
Enable:
-
This bit is used to enable/disable the transfer in the DMA LCD channel
when OMAP external LCD controller is selected.
Enable = 1: The transfer starts.
Enable = 0: The transfer stops and is reset.
This bit is automatically cleared by the DMA hardware once the transfer is
completed. However, if AUTO_INIT = 1 and REPEAT = 1, the channel con-
tinues without being disabled. Clearing of this bit by the DMA has priority
over a write by the processor. If both occur simultaneously, the configura-
tion write is discarded.
Note:
If the software must use this bit as a flag, it must do a back to back read to
make sure that correct value of this enable bit is latched. This is because the
enable bit can be asynchronously reset at the end of channel transfer, and
a wrong value may send back when this risk condition happens.
AUTO_INIT: Autoinitialization at the end of the transfer
-
auto_init = 1: LCD channel is in autoinitialization mode. Once the current
transfer is complete, the channel automatically reinitializes itself and starts
a new transfer, if REPEAT or END_PROG bits is set. Else, if neither RE-
PEAT nor END_PROG equals 1, wait for the END_PROG to be set to 1 to
reload the channel with a new context and let the transfer restart.
auto_init = 0: LCD channel is in non-autoinitialization mode. The DMA
channel stops at the end of the current transfer.
REPEAT: repetitive operation
-
Repeat = 1: When LCD channel is in autoinitialization mode, once the cur-
rent transfer is complete the channel automatically reinitializes itself and
starts a new transfer with the previous or a new context depending on the
end_prog bit (0/1).
Repeat = 0: When LCD channel is in autoinitialization mode, once the cur-
rent transfer is complete the channel automatically reinitializes itself and
starts a new transfer only if END_PROG = 1.
The repeat bit is not considered if AUTO_INIT = 0.
SPRU755B
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